JP7761382B2 - Image sensor with color separation lens array and electronic device including same - Google Patents

Description

The present invention relates to an image sensor having a color separation lens array and an electronic device including the image sensor. More specifically, the present invention relates to an image sensor having a color separation lens array that can separate and focus incident light according to wavelength, and an electronic device including the image sensor.

Image sensors generally use color filters to detect the color of incident light. However, color filters absorb light of colors other than the one they detect, reducing light utilization efficiency. For example, when using an RGB color filter, only one-third of the incident light is transmitted and the remaining two-thirds is absorbed, resulting in a light utilization efficiency of only about 33%. Therefore, in the case of color display devices and color image sensors, most of the light loss occurs in the color filters.

U.S. Patent No. 9,653,501

The problem that this invention aims to solve is to provide an image sensor with improved light utilization efficiency by using a color separation lens array that can separate and focus incident light according to wavelength.

The problem that the present invention aims to solve is also to provide an electronic device that includes such an image sensor.

An image sensor according to an embodiment includes: a sensor substrate including first and second photosensitive cells that detect light; and a color separation lens array including a first region facing the first photosensitive cells and including first nanoposts, and a second region facing the second photosensitive cells and including second nanoposts, wherein the first and second nanoposts are different from each other in at least one of shape, size, and arrangement, and the first and second nanoposts may split light having a first wavelength and light having a second wavelength, which are different from each other, of incident light entering the color separation lens array into different directions, and form phase distributions of the light focused on the first and second photosensitive cells at positions after passing through the first and second regions.
The first nanoposts and the second nanoposts can cause the light of the first wavelength to form a phase distribution of 2Nπ at a position corresponding to the center of the first photosensitive cell and a phase distribution of (2N−1)π at a position corresponding to the center of the second photosensitive cell, immediately after passing through the color separation lens array, where N is an integer greater than 0.

The first nanoposts and the second nanoposts can form a (2M-1)π phase distribution at the position corresponding to the center of the first photosensitive cell and a 2Mπ phase distribution at the position corresponding to the center of the second photosensitive cell, immediately after the light has passed through the color separation lens array. Here, M is an integer greater than 0.

The image sensor may further include a spacer layer disposed between the sensor substrate and the color separation lens array, forming a distance between the sensor substrate and the color separation lens array.

The spacer layer may have a thickness corresponding to the color separation lens array at the center wavelength of the wavelength band of incident light that is color separated by the color separation lens array.

Let h _t be the theoretical thickness of the spacer layer, p be the pitch of the photosensitive cells, n be the refractive index of the spacer layer, and λ ₀ be the central wavelength of the wavelength band of light that is color-separated by the color separation lens array. Then, the theoretical thickness h _t of the spacer layer is given by:

and the actual thickness h of the spacer layer is h _t −p≦h≦h _t +p.
The sensor substrate may further include third and fourth photosensitive cells that detect light, and the color separation lens array may include a third region facing the third photosensitive cells and including third nanoposts, and a fourth region facing the fourth photosensitive cells and including fourth nanoposts, and the third nanoposts and the fourth nanoposts may be different from each other in at least one of shape, size, and arrangement.

The first to fourth nanoposts can split light beams of different wavelengths, that is, first, second, and third wavelengths, from the light beams incident on the color separation lens array into different directions, and form a phase distribution at the position where the light beams pass through the first to fourth regions, such that the light beams of the first wavelength are focused on the first and fourth photosensitive cells, the light beams of the second wavelength are focused on the second photosensitive cells, and the light beams of the third wavelength are focused on the third photosensitive cells.

The first wavelength is green light, the second wavelength is blue light, and the third wavelength is also red light.

The first to fourth nanoposts may be configured so that, immediately after passing through the color separation lens array, the light of the first wavelength forms a phase distribution of 2Nπ at positions corresponding to the central parts of the first and fourth photosensitive cells, and a phase distribution of (2N-1)π at positions corresponding to the central parts of the second and third photosensitive cells. Here, N is an integer greater than 0.

The first to fourth nanoposts may be configured so that, immediately after passing through the color separation lens array, the light of the second wavelength forms a phase distribution of (2M-1)π at positions corresponding to the central parts of the first and fourth photosensitive cells, a phase distribution of 2Mπ at a position corresponding to the central part of the second photosensitive cell, and a phase distribution greater than (2M-2)π and smaller than (2M-1)π at a position corresponding to the central part of the third photosensitive cell.

The first to fourth nanoposts may be configured so that, immediately after passing through the color separation lens array, the light of the third wavelength forms a phase distribution of (2L-1)π at positions corresponding to the centers of the first and fourth photosensitive cells, a phase distribution of 2Lπ at a position corresponding to the center of the third photosensitive cell, and a phase distribution greater than (2L-2)π and less than (2L-1)π at a position corresponding to the center of the second photosensitive cell. Here, L is an integer greater than 0.

The image sensor has a pixel array structure in which a plurality of unit pixels, including red, green, and blue pixels, are arranged in a Bayer pattern, and the nanoposts provided in the regions corresponding to the green pixels in the first through fourth regions may have different distribution patterns along a first direction and a second direction perpendicular to the first direction.

In the first to fourth regions, the nanoposts provided in the regions corresponding to the blue and red pixels may have a symmetrical distribution pattern along the first and second directions.

In the first through fourth regions, the nanoposts located in the center of the region corresponding to the green pixel may have a larger cross-sectional area than the nanoposts provided in the regions corresponding to the pixels of other colors.

In the first through fourth regions, the nanoposts provided in the regions corresponding to the green pixels may have a larger cross-sectional area in the center than in the periphery.

The color separation lens array may further include a plurality of first regions and a plurality of second regions that are arranged to protrude from the edge of the sensor substrate and do not face any of the photosensitive cells of the sensor substrate in the vertical direction.

At least one of the first nanoposts and the second nanoposts includes a lower post and an upper post stacked on the lower post, and the lower post and the upper post are stacked so as to be offset from each other.

The degree to which the lower post and the upper post are misaligned with each other increases as you move from the center to the periphery of the image sensor.

An image sensor according to another embodiment includes a sensor substrate including a plurality of first photosensitive cells and a plurality of second photosensitive cells alternately arranged along a first row, and a plurality of third photosensitive cells and a plurality of fourth photosensitive cells alternately arranged along a second row adjacent to the first row; and a color separation lens array including a plurality of first regions facing the plurality of first photosensitive cells, each including a first nanopost; a plurality of second regions facing the plurality of second photosensitive cells, each including a second nanopost; a plurality of third regions facing the plurality of third photosensitive cells, each including a third nanopost; and a plurality of fourth regions facing the plurality of fourth photosensitive cells, each including a fourth nanopost. The shapes, sizes, and arrangements of the first to fourth nanoposts may be set so that light of a first wavelength is focused on a first photosensitive cell located below the first region, light of a second wavelength is branched to a second photosensitive cell adjacent to the first photosensitive cell in the horizontal direction, light of a third wavelength is branched to a third photosensitive cell adjacent to the first photosensitive cell in the vertical direction, and among the light incident on the second region, light of the second wavelength is focused on a second photosensitive cell located immediately below the second region, light of the first wavelength is branched to a first photosensitive cell adjacent to the second photosensitive cell in the horizontal direction and a fourth photosensitive cell adjacent to the second photosensitive cell in the vertical direction, and light of a third wavelength is branched to a third photosensitive cell diagonally adjacent to the second photosensitive cell.

The light of the first wavelength is green light, the light of the second wavelength is blue light, and the light of the third wavelength is also red light.

An electronic device according to another embodiment may include an imaging unit that focuses light reflected from a subject to form an optical image, and any one of the image sensors described above that converts the optical image formed by the imaging unit into an electrical signal.

The electronic device may be a smartphone, a mobile phone, a PDA (personal digital assistant), a laptop, a PC (personal computer), a home appliance, a security camera, a medical camera, a car, or an Internet of Things (IoT) device.

The disclosed color separation lens array can separate and focus incident light by wavelength without absorbing or blocking it, thereby improving the light utilization efficiency of the image sensor. Furthermore, an image sensor employing the disclosed color separation lens array can maintain the Bayer pattern method commonly used in image sensors, and can utilize the pixel structure and image processing algorithms of existing image sensors. Furthermore, an image sensor employing the disclosed color separation lens array does not require a separate microlens to focus light onto the pixels.

FIG. 1 is a block diagram of an image sensor according to one embodiment. 1 is a diagram illustrating various exemplary pixel arrangements of a pixel array of an image sensor; 1 is a diagram illustrating various exemplary pixel arrangements of a pixel array of an image sensor; 1 is a diagram illustrating various exemplary pixel arrangements of a pixel array of an image sensor; 1 is a conceptual diagram illustrating the general structure and operation of a color separation lens array according to one embodiment. 1A-1C are schematic cross-sectional views of a pixel array of an image sensor according to one embodiment, shown at different cross sections; 1A-1C are schematic cross-sectional views of a pixel array of an image sensor according to one embodiment, shown at different cross sections; FIG. 2 is a plan view schematically illustrating an arrangement of photosensitive cells in a pixel array of an image sensor. 10 is a plan view illustrating an example of a pixel array of an image sensor in which a plurality of nanoposts are arranged in a plurality of regions of a color separation lens array. FIG. 5C is an enlarged plan view showing a portion of FIG. 5B in detail. 10 is a diagram showing a phase distribution of blue light that has passed through a color separation lens array. 10 is a diagram showing a computer-simulated blue light focusing distribution in a photosensitive cell facing a color separation lens array; 10 is a diagram illustrating an example of a second region of a color separation lens array corresponding to a blue pixel and the traveling direction of blue light incident on the periphery thereof; 10 is a diagram illustrating an example of a microlens array that functions equivalently to a color separation lens array for blue light. 10 is a diagram showing the phase distribution of green light that has passed through a color separation lens array. 10 is a diagram showing a computer-simulated green light focusing distribution in a photosensitive cell facing a color separation lens array; 10 is a diagram illustrating an example of a first region of a color separation lens array corresponding to a green pixel and the traveling direction of green light incident on the periphery thereof; 10 is a diagram illustrating an example of a microlens array that functions equivalently to a color separation lens array for green light. 10 is a diagram showing the phase distribution of red light that has passed through a color separation lens array. 10 is a diagram showing a computer-simulated red light focusing distribution in a photosensitive cell facing a color separation lens array; 10 is a diagram illustrating an example of a third region of a color separation lens array corresponding to a red pixel and the traveling direction of red light incident on the periphery thereof; 10 is a diagram illustrating an example of a microlens array that functions equivalently to a color separation lens array for red light. 10 is a diagram illustrating an example of the traveling direction of light incident on a region corresponding to a blue pixel, according to color; 10 is a diagram illustrating an example of the traveling direction of light incident on a region corresponding to a green pixel according to color; 10 is a diagram illustrating an example of the traveling direction of light incident on a region corresponding to a red pixel according to color; 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and a sensor substrate when the pitch of the photosensitive cells is 0.7 μm; 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and a sensor substrate when the pitch of the photosensitive cells is 0.7 μm; 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and a sensor substrate when the pitch of the photosensitive cells is 0.7 μm; 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and a sensor substrate when the pitch of the photosensitive cells is 0.7 μm; 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and a sensor substrate when the pitch of the photosensitive cells is 0.7 μm; 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and a sensor substrate when the pitch of the photosensitive cells is 0.8 μm; 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and a sensor substrate when the pitch of the photosensitive cells is 0.8 μm; 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and a sensor substrate when the pitch of the photosensitive cells is 0.8 μm; 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and a sensor substrate when the pitch of the photosensitive cells is 0.8 μm; 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and a sensor substrate when the pitch of the photosensitive cells is 0.8 μm; 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and the sensor substrate when the pitch of the photosensitive cells is 1.0 μm; 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and the sensor substrate when the pitch of the photosensitive cells is 1.0 μm; 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and the sensor substrate when the pitch of the photosensitive cells is 1.0 μm; 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and the sensor substrate when the pitch of the photosensitive cells is 1.0 μm; 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and the sensor substrate when the pitch of the photosensitive cells is 1.0 μm; 1A and 1B are perspective views illustrating exemplary configurations of nanoposts that may also be employed in a color separation lens array of an image sensor according to an embodiment. 10A and 10B are plan views illustrating exemplary shapes of nanoposts that may also be employed in color separation lens arrays of image sensors according to other embodiments. 10A and 10B are plan views illustrating exemplary shapes of nanoposts that may also be employed in color separation lens arrays of image sensors according to other embodiments. 10A and 10B are plan views illustrating exemplary shapes of nanoposts that may also be employed in color separation lens arrays of image sensors according to other embodiments. 10A and 10B are plan views illustrating exemplary shapes of nanoposts that may also be employed in color separation lens arrays of image sensors according to other embodiments. 10A and 10B are plan views illustrating exemplary shapes of nanoposts that may also be employed in color separation lens arrays of image sensors according to other embodiments. 10A and 10B are plan views illustrating exemplary shapes of nanoposts that may also be employed in color separation lens arrays of image sensors according to other embodiments. 10A and 10B are plan views illustrating exemplary shapes of nanoposts that may also be employed in color separation lens arrays of image sensors according to other embodiments. 10A and 10B are plan views illustrating exemplary shapes of nanoposts that may also be employed in color separation lens arrays of image sensors according to other embodiments. 10 is a plan view illustrating an example of an arrangement of a plurality of nanoposts forming a color separation lens array of an image sensor according to another embodiment. 10 is a plan view illustrating an exemplary arrangement of a plurality of nanoposts forming a color separation lens array of an image sensor according to yet another embodiment. 10 is a plan view illustrating an exemplary arrangement of a plurality of nanoposts forming a color separation lens array of an image sensor according to yet another embodiment. 10 is a plan view illustrating an exemplary arrangement of a plurality of nanoposts forming a color separation lens array of an image sensor according to yet another embodiment. 19 is a graph showing an example of the spectral distribution of light incident on red, green, and blue pixels of the image sensor having the color separation lens array of FIG. 18; 10A to 10C are cross-sectional views showing a schematic structure of a pixel array of an image sensor according to another embodiment, each taken along a different cross section. 10A to 10C are cross-sectional views showing a schematic structure of a pixel array of an image sensor according to another embodiment, each taken along a different cross section. 10 is a graph illustrating an example of spectral distributions of light incident on red, green, and blue pixels of an image sensor according to an embodiment, in which color filters are provided; 10 is a graph illustrating an example of spectral distributions of light incident on red, green, and blue pixels of an image sensor according to an embodiment, in the case where no color filters are provided; 10A and 10B are plan views illustrating an example of a color separation lens array according to another embodiment. 24 is a cross-sectional view showing a schematic structure of a pixel array of an image sensor including the color separation lens array shown in FIG. 23. FIG. 10 is a cross-sectional view showing a schematic structure of an image sensor according to yet another embodiment. 26A and 26B are perspective views illustrating exemplary shapes of nanoposts employed in the color separation lens array of the image sensor of FIG. 25. 1 is a block diagram that schematically illustrates an electronic device including an image sensor according to one embodiment. 1 is a diagram illustrating an example of an electronic device to which an image sensor according to an embodiment is applied. 1 is a diagram illustrating another example of an electronic device to which an image sensor according to an embodiment is applied. 1 is a diagram illustrating yet another example of an electronic device to which an image sensor according to an embodiment is applied. 1 is a diagram illustrating yet another example of an electronic device to which an image sensor according to an embodiment is applied. 1 is a diagram illustrating yet another example of an electronic device to which an image sensor according to an embodiment is applied. 1 is a diagram illustrating yet another example of an electronic device to which an image sensor according to an embodiment is applied. 1 is a diagram illustrating yet another example of an electronic device to which an image sensor according to an embodiment is applied. 1 is a diagram illustrating yet another example of an electronic device to which an image sensor according to an embodiment is applied. 1 is a diagram illustrating yet another example of an electronic device to which an image sensor according to an embodiment is applied. 1 is a diagram illustrating yet another example of an electronic device to which an image sensor according to an embodiment is applied. 1 is a diagram illustrating yet another example of an electronic device to which an image sensor according to an embodiment is applied.

Hereinafter, an image sensor having a color separation lens array and an electronic device including the same will be described in detail with reference to the accompanying drawings. The described embodiments are merely exemplary, and various modifications are possible from such embodiments. In the following drawings, the same reference numerals refer to the same components, and the size of each component may be exaggerated in the drawings for clarity and convenience of explanation.

In the following, the expressions "top" or "above" include not only things that are in contact and immediately above, below, left or right of something, but also things that are not in contact and are above, below, left or right of something.

Terms such as "first" and "second" may be used to describe various components, but are used only to distinguish one component from another. Such terms do not limit the components to differences in material or structure.

Unless the context clearly dictates otherwise, singular expressions also include plural expressions. Furthermore, when a part "comprises" a certain element, this does not mean that it excludes other elements, but that it may further include other elements, unless otherwise specified to the contrary.

In addition, terms such as "unit" and "module" used in the specification refer to units that process functions or operations, and may be realized by hardware or software, or by a combination of hardware and software.

The use of the term "said" and similar referents may refer to both the singular and the plural.

The steps constituting the method may be performed in any suitable order unless expressly stated to be performed in the order described. Furthermore, the use of all exemplary terms (e.g., "for example") is merely intended to illustrate the technical concept in detail and does not limit the scope of the claims, as such terms are not intended to limit the scope of the invention.

FIG. 1 is a schematic block diagram of an image sensor according to one embodiment. Referring to FIG. 1, the image sensor 1000 may include a pixel array 1100, a timing controller 1010, a row decoder 1020, and an output circuit 1030. The image sensor 1000 may be a CCD (charge coupled device) image sensor or a CMOS (complementary metal oxide semiconductor) image sensor.

The pixel array 1100 includes pixels arranged two-dimensionally along a plurality of rows and columns. The row decoder 1020 selects one of the rows of the pixel array 1100 in response to a row address signal output from the timing controller 1010. The output circuit 1030 outputs a photo-sensing signal in units of columns from a plurality of pixels arranged along the selected row. To this end, the output circuit 1030 may include a column decoder and an analog-to-digital converter (ADC). For example, the output circuit 1030 may include a column decoder and a plurality of ADCs arranged for each column between the pixel array 1100, or a single ADC arranged at the output end of the column decoder. The timing controller 1010, the row decoder 1020, and the output circuit 1030 may be implemented on a single chip or on separate chips. A processor for processing the video signal output via the output circuit 1030 is also implemented on a single chip together with the timing controller 1010, row decoder 1020, and output circuit 1030.

The pixel array 1100 may include multiple pixels that sense light of different wavelengths. The pixels may be arranged in various ways, such as those shown in Figures 2A to 2C.

2A shows a Bayer pattern commonly used in image sensors 1000. Referring to FIG. 2, one unit pixel includes four quadrant regions, with the first through fourth quadrant regions being a blue pixel B, a green pixel G, a red pixel R, and a green pixel G, respectively. Such unit pixels are arranged two-dimensionally in a repeated manner along a first direction (X direction) and a second direction (Y direction). In other words, within a 2x2 array of unit pixels, two green pixels G are arranged in one diagonal direction, and one blue pixel B and one red pixel R are arranged in the other diagonal direction. Looking at the overall pixel arrangement, a first row in which a plurality of green pixels G and a plurality of blue pixels B are alternately arranged along the first direction, and a second row in which a plurality of red pixels R and a plurality of green pixels G are alternately arranged along the first direction are repeatedly arranged.

However, the arrangement of the pixel array 1100 is not limited to the Bayer pattern, and various other arrangements are possible. For example, referring to FIG. 2B, a CYGM arrangement is also possible, in which a magenta pixel (M), a cyan pixel (C), a yellow pixel (Y), and a green pixel (G) constitute one unit pixel. Referring to FIG. 2C, an RGBW arrangement is also possible, in which a green pixel G, a red pixel R, a blue pixel B, and a white pixel (W) constitute one unit pixel. Although not shown, the unit pixels may also have a 3x2 array. Alternatively, the pixels of the pixel array 1100 may be arranged in various other ways depending on the color characteristics of the image sensor 1000. For convenience, the following description will be given assuming that the pixel array 1100 of the image sensor 1000 has a Bayer pattern. However, the principles of the embodiments described below may be applied to pixel arrangements other than the Bayer pattern.

According to one embodiment, the pixel array 1100 of the image sensor 1000 may include a color separation lens array configured to focus light of a corresponding color onto each pixel. FIG. 3 is a conceptual diagram illustrating the general structure and operation of a color separation lens array according to one embodiment. Referring to FIG. 3, the color separation lens array 130 includes nanoposts NPs arranged on the same plane according to a predetermined rule. Such a color separation lens array 130 is also disposed on the spacer layer 120.

Here, this rule applies to parameters such as the shape, size (width, height), spacing, and arrangement of the nanoposts NP, and is also determined by the target phase distribution TP embodied by the color separation lens array 130 for the incident light L _i . The target phase distribution TP is also determined by taking into account the target regions R1 and R2 that separate and focus the wavelengths of the incident light L _i . Although the target phase distribution TP is shown between the color separation lens array 130 and the target regions R1 and R2, this is merely for convenience of illustration. The actual target phase distribution TP refers to the phase distribution at a position immediately after the incident light L _i passes through the color separation lens array 130, for example, at the lower surface of the color separation lens array 130 or the upper surface of the spacer layer 120.

The color separation lens array 130 may include a first region 131 and a second region 132, each of which may include one or more nanoposts NPs. The first region 131 and the second region 132 may be arranged to face the first target region R1 and the second target region R2, respectively, and may correspond one-to-one. While the first region 131 and the second region 132 are illustrated as each having three nanoposts NPs, this is merely an example. Furthermore, the nanoposts NPs are illustrated as being entirely located within one of the first region 131 and the second region 132, but this is not limiting. Some nanoposts NPs may also be located at the boundary between the first region 131 and the second region 132. The nanoposts NPs arranged in the first region 131 are first nanoposts, and the nanoposts NPs arranged in the second region 132 are second nanoposts (this also applies to other embodiments).

The nanoposts NP of the color separation lens array 130 can form a phase distribution that splits and focuses light of different wavelengths included in the incident light _Li in different directions. For example, the shapes, sizes, and arrangements of the nanoposts NP distributed in the first region 131 and the second region 132 are determined so that light of a first wavelength _Lλ1 included in the incident light _Li has a first phase distribution and light of a second wavelength _Lλ2 has a second phase distribution to form a target phase distribution TP. Due to this target phase distribution TP, the light of the first wavelength _Lλ1 and the light of the second wavelength _Lλ2 can be focused on the nanoposts NP and target regions R1 and R2 located at a predetermined distance A, respectively.

The arrangement of the nanoposts NPs in the first region 131 may be different from the arrangement of the nanoposts NPs in the second region 132. In other words, any one of the shape, size, and arrangement of the first nanoposts NPs provided in the first region 131 may be different from the shape, size, and arrangement of the second nanoposts NPs provided in the second region 132.

The nanopost NPs may have a sub-wavelength shape smaller than the wavelength band to be split. The nanopost NPs may have a shape smaller than the shorter wavelength of the first wavelength or the second wavelength, and when the incident light _Li is visible light, may have a size smaller than 400 nm, 300 nm, or 200 nm, for example.

Nanopost NPs can also be made of a material with a higher refractive index than the surrounding material. For example, nanopost NPs can be made of single-crystal silicon (c-Si), polysilicon (p-Si), amorphous silicon (a-Si), III-V compound semiconductors (GaP, GaN, GaAs, etc.), SiC, TiO ₂ , SiN, and/or combinations thereof. Nanopost NPs, which have a refractive index different from that of the surrounding material, can change the phase of light passing through them. This is due to the phase delay caused by the subwavelength shape and dimensions, and the degree of phase delay is determined by the detailed shape and arrangement of the nanopost NPs. The surrounding material can also be a dielectric material with a lower refractive index than the nanopost NPs, such as SiO ₂ or air.

The first wavelength λ1 and the second wavelength λ2 may be in the visible light wavelength band, but are not limited to this, and various wavelength bands can be realized depending on the rules regarding the shape, size, spacing, arrangement, etc. of the arranged nanoposts NP. Figure 3 shows an example of two wavelengths being branched and focused, but this is not limited to this, and incident light can be branched in three or more directions depending on the wavelength and still be focused.

Below, we will provide a more detailed explanation of an example in which the aforementioned color separation lens array 130 is applied to the pixel array 1100 of the image sensor 1000.

Figures 4A and 4B are cross-sectional views of a pixel array according to one embodiment, Figure 5A is a plan view showing the arrangement of photosensitive cells in the pixel array, and Figure 5B is a plan view showing an example of the arrangement of nanoposts in a color separation lens array.

Referring to Figures 4A and 4B, the pixel array 1100 includes a sensor substrate 110 including a plurality of photosensitive cells 111, 112, 113, and 114 that sense light, a transparent spacer layer 120 disposed on the sensor substrate 110, and a color separation lens array 130 disposed on the spacer layer 120.

The sensor substrate 110 may include first, second, third, and fourth photosensitive cells 111, 112, 113, and 114 that convert light into electrical signals. For example, as shown in FIG. 4A , the first and second photosensitive cells 111 and 112 may be alternately arranged along a first direction (X direction), and in a cross section at a different position in the Y direction, as shown in FIG. 4B , the third and fourth photosensitive cells 113 and 114 may be alternately arranged. Such area division is intended to divide and sense incident light in pixel units. For example, the first and fourth photosensitive cells 111 and 114 may sense light of a first wavelength corresponding to a first pixel, the second photosensitive cell 112 may sense light of a second wavelength corresponding to a second pixel, and the third photosensitive cell 113 may sense light of a third wavelength corresponding to a third pixel. In the following description, the first wavelength light is green light, the second wavelength light is blue light, and the third wavelength light is red light, and the first pixel, second pixel, and third pixel are green pixel G, blue pixel B, and red pixel R, respectively. Although not shown, a separation film for cell separation may be further formed at the boundary between cells.

The spacer layer 120 supports the color separation lens array 130 and maintains a constant distance between the sensor substrate 110 and the color separation lens array 130. The spacer layer 120 is made of a material that is transparent to visible light. For example, the spacer layer 120 may be made of a dielectric material that has a refractive index lower than that of the nanoposts NPs of the color separation lens array 130 and low absorption in the visible light range, such as SiO ₂ or siloxane-based spin-on glass (SOG).

The color separation lens array 130 includes nanopost NPs arranged according to a predetermined pattern. Although not shown, the color separation lens array 130 may further include a protective layer to protect the nanopost NPs. The protective layer may be made of a dielectric material with a refractive index lower than that of the material forming the nanopost NPs.

The color separation lens array 130 is divided into a plurality of regions 131, 132, 133, and 134 that face the plurality of photosensitive cells 111, 112, 113, and 114 in a one-to-one correspondence. One or more nanoposts NPs are arranged in each of the plurality of regions 131, 132, 133, and 134, and any one of the shape, size, and arrangement may differ depending on the region.

The color separation lens array 130 is divided into regions so that light of a first wavelength is split and focused onto the first photosensitive cell 111 and the fourth photosensitive cell 114, light of a second wavelength is split and focused onto the second photosensitive cell 112, and light of a third wavelength is split and focused onto the third photosensitive cell 113, and the size, shape, and arrangement of the nanoposts NP are determined for each region.

When the pixel array 1100 has the Bayer pattern shown in FIG. 2A, the first photosensitive cell 111 and the fourth photosensitive cell 114 in FIG. 5A correspond to the green pixel G, the second photosensitive cell 112 corresponds to the blue pixel B, and the third photosensitive cell 113 corresponds to the red pixel R. Referring to FIG. 5B, the first region 131 and the fourth region 134 of the color separation lens array 130 correspond to the green pixel G, the second region 132 corresponds to the blue pixel B, and the third region 133 corresponds to the red pixel R. Therefore, the color separation lens array 130 includes a plurality of unit pattern arrays arranged two-dimensionally, and each unit pattern array includes the first region 131, the second region 132, the third region 133, and the fourth region 134 arranged in a 2x2 pattern.

As shown in FIG. 5B , the first region 131 and fourth region 134 corresponding to the green pixel G, the second region 132 corresponding to the blue pixel B, and the third region 133 corresponding to the red pixel R may include cylindrical nanoposts NPs with circular cross sections. The nanoposts NPs arranged in the third region 133 are third nanoposts, and the nanoposts NPs arranged in the fourth region 134 are fourth nanoposts (this is also true in other embodiments). Nanoposts NPs with different cross-sectional areas are arranged in the centers of the first region 131, second region 132, third region 133, and fourth region 134, and nanoposts NPs may also be arranged at the centers of the inter-pixel boundary lines and at the intersections of the pixel boundary lines. The cross-sectional areas of the nanoposts NPs arranged at the inter-pixel boundary lines may be narrower than those of the nanoposts NPs arranged in the center of the pixels.

Figure 5C shows in detail the nanopost NP arrangement in a portion of Figure 5B, i.e., the first region 131 to the fourth region 134 that constitute the unit pattern array. In Figure 5C, the nanopost NPs are labeled p1 to p9 according to their detailed positions within the unit pattern array. Referring to Figure 5C, the cross-sectional areas of the nanopost p1 located at the center of the first region 131 and the nanopost p4 located at the center of the fourth region 134 are larger than the cross-sectional areas of the nanopost p2 located at the center of the second region 132 and the nanopost p3 located at the center of the third region 133, and the cross-sectional area of the nanopost p2 located at the center of the second region 132 is larger than the cross-sectional area of the nanopost p3 located at the center of the third region 133. However, this is merely one example, and nanopost NPs of various shapes, sizes, and arrangements can be applied as needed.

The nanoposts NP in the first region 131 and the fourth region 134 corresponding to the green pixel G may have different distribution patterns along the first direction (X direction) and the second direction (Y direction). For example, the nanoposts NP arranged in the first region 131 and the fourth region 134 may have different size arrangements along the first direction (X direction) and the second direction (Y direction). As shown in FIG. 5C , the cross-sectional area of the nanopost p5 located at the boundary between the first region 131 and the second region 132 adjacent to it in the first direction (X direction) is different from the cross-sectional area of the nanopost p6 located at the boundary between the first region 131 and the third region 133 adjacent to it in the second direction (Y direction). Similarly, the cross-sectional area of nanopost p7 located at the boundary between the fourth region 134 and the third region 133 adjacent to it in the first direction (X direction) is different from the cross-sectional area of nanopost p8 located at the boundary between the fourth region 134 and the second region 132 adjacent to it in the second direction (Y direction).

Meanwhile, the nanoposts NP arranged in the second region 132 corresponding to the blue pixel B and the third region 133 corresponding to the red pixel R may have a symmetrical distribution pattern along the first direction (X direction) and the second direction (Y direction). As shown in FIG. 5C , the cross-sectional areas of nanopost p5 located at the boundary between pixels adjacent to the second region 132 in the first direction (X direction) and nanopost p8 located at the boundary between pixels adjacent to the second region 132 in the second direction (Y direction) are the same in the nanopost NP. Also, the cross-sectional areas of nanopost p7 located at the boundary between pixels adjacent to the third region 133 in the first direction (X direction) and nanopost p6 located at the boundary between pixels adjacent to the third region 133 in the second direction (Y direction) are the same in the nanopost NP.

On the other hand, nanoposts p9 located at the four corners of each of the first region 131, second region 132, third region 133, and fourth region 134, i.e., at the intersections of the four regions, have the same cross-sectional area.

This distribution results from the Bayer pattern pixel arrangement. For both blue and red pixels, adjacent pixels in the first direction (X direction) and the second direction (Y direction) are identical as green pixels G. Meanwhile, for green pixels G corresponding to the first region 131, adjacent pixels in the first direction (X direction) are blue pixels B and adjacent pixels in the second direction (Y direction) are red pixels R. For green pixels G corresponding to the fourth region 134, adjacent pixels in the first direction (X direction) are red pixels R and adjacent pixels in the second direction (Y direction) are blue pixels B. Furthermore, for green pixels G corresponding to the first and fourth regions 131 and 134, adjacent pixels in the four diagonal directions are identical as green pixels G. For blue pixels B corresponding to the second region 132, adjacent pixels in the four diagonal directions are identical as red pixels R. For red pixels R corresponding to the third region 133, adjacent pixels in the four diagonal directions are identical as blue pixels B. Therefore, in the second region 132 and the third region 133 corresponding to the blue pixel B and the red pixel R, respectively, the nanoposts NP are arranged in a 4-fold symmetry form, and in the first region 131 and the fourth region 134 corresponding to the green pixel G, the nanoposts NP are arranged in a 2-fold symmetry form. In particular, the first region 131 and the fourth region 134 are rotated 90° with respect to each other.

While the nanoposts NP are illustrated as having a symmetrical circular cross-sectional shape, this is not limiting and some nanoposts may have asymmetric cross-sectional shapes. For example, the first region 131 and fourth region 134 corresponding to the green pixel G may employ nanoposts having asymmetric cross-sectional shapes with different widths in the first direction (X direction) and the second direction (Y direction), while the second region 132 and third region 133 corresponding to the blue pixel B and the red pixel R, respectively, may employ nanoposts having symmetric cross-sectional shapes with the same widths in the first direction (X direction) and the second direction (Y direction).

The arrangement pattern of the color separation lens array 130 is one example for realizing a target phase distribution in which light of a first wavelength is split and focused by the first photosensitive cell 111 and the fourth photosensitive cell 114, light of a second wavelength is split and focused by the second photosensitive cell 112, and light of a third wavelength is split and focused by the third photosensitive cell 113, but is not limited to the pattern shown in the figure.

The shape, size, and arrangement of the nanoposts NP provided in each region of the color separation lens array 130 can be determined so that, at the position where the light of the first wavelength passes through the color separation lens array 130, it forms a phase where it is focused on the first photosensitive cell 111 and the fourth photosensitive cell 114, and does not travel to the adjacent second photosensitive cell 112 and third photosensitive cell 113.

Similarly, the shape, size, and arrangement of the nanoposts NP provided in each region of the color separation lens array 130 can be determined so that, at a position where the light of the second wavelength has passed through the color separation lens array 130, it forms a phase in which it is focused on the second photosensitive cell 112 and does not travel to the adjacent first photosensitive cell 111, third photosensitive cell 113, and fourth photosensitive cell 114.

Similarly, the shape, size, and arrangement of the nanoposts NP provided in each region of the color separation lens array 130 can be determined so that, at a position where the light of the third wavelength has passed through the color separation lens array 130, it forms a phase in which the light is focused on the third photosensitive cell 113 and does not travel to the adjacent first photosensitive cell 111, second photosensitive cell 112, and fourth photosensitive cell 114.

The shape, size, and/or arrangement of the nanoposts NPs can be determined to satisfy all of these conditions, and such a color separation lens array 130 can be configured so that light immediately after passing through it has the following target phase distribution: The phase of the light of the first wavelength at a position immediately after passing through the color separation lens array 130, in other words, at the lower surface of the color separation lens array 130 or the upper surface of the spacer layer 120, is 2Nπ at the center of the first region 131 corresponding to the first photosensitive cell 111 and at the center of the fourth region 134 corresponding to the fourth photosensitive cell 114, and also has a distribution exhibiting a phase of (2N-1)π at the center of the second region 132 corresponding to the second photosensitive cell 112 and at the center of the third region 133 corresponding to the third photosensitive cell 113. Here, N is an integer greater than 0. In other words, immediately after passing through the color separation lens array 130, the phase of the first wavelength light is maximum at the center of the first region 131 and the center of the fourth region 134, and gradually decreases concentrically with increasing distance from the center of the first region 131 and the center of the fourth region 134, reaching minimums at the centers of the second region 132 and the third region 133. For example, when N = 1, the phase of green light after passing through the color separation lens array 130 is 2π at the center of the first region 131 and the center of the fourth region 134, and is also π at the center of the second region 132 and the center of the third region 133. Here, the phase refers to a relative phase value related to the phase of the light immediately before passing through the nanopost NP.

Furthermore, immediately after passing through the color separation lens array 130, the phase of the light of the second wavelength is 2Mπ at the center of the second region 132 corresponding to the second photosensitive cell 112, is (2M-1)π at the center of the first region 131 corresponding to the first photosensitive cell 111 and at the center of the fourth region 134 corresponding to the fourth photosensitive cell 114, and is greater than (2M-2)π and smaller than (2M-1)π at the center of the third region 133 corresponding to the third photosensitive cell 113. Here, M is an integer greater than 0. In other words, immediately after passing through the color separation lens array 130, the phase of the light of the second wavelength is maximum at the center of the second region 132, and gradually decreases concentrically with increasing distance from the center of the second region 132, reaching local minimums at the centers of the first region 131, the fourth region 134, and the third region 133. For example, when M = 1, the phase of blue light at the position where it has passed through the color separation lens array 130 is 2π at the center of the second region 132, π at the center of the first region 131 and the center of the fourth region 134, and approximately 0.2π to 0.7π at the center of the third region 133.

Similarly, immediately after passing through the color separation lens array 130, the phase of the light of the third wavelength is 2Lπ at the center of the third region 133 corresponding to the third photosensitive cell 113, is (2L-1)π at the centers of the first region 131 corresponding to the first photosensitive cell 111 and the fourth region 134 corresponding to the fourth photosensitive cell 114, and is greater than (2L-2)π and smaller than (2L-1)π at the center of the second region 132 corresponding to the second photosensitive cell 112. Here, L is an integer greater than 0. In other words, immediately after passing through the color separation lens array 130, the phase of the light of the third wavelength is maximum at the center of the third region 133, and gradually decreases concentrically with increasing distance from the center of the third region 133, reaching local minimums at the centers of the first region 131, the fourth region 134, and the second region 132. For example, when L = 1, the phase of red light at the position where it has passed through the color separation lens array 130 is 2π at the center of the third region 133, π at the center of the first region 131 and the center of the fourth region 134, and approximately 0.2π to 0.7π at the center of the second region 132.

As mentioned above, the target phase distribution refers to the phase distribution of light at a position immediately after it has passed through the color separation lens array 130. If the light that has passed through the color separation lens array 130 has such a phase distribution, the light of the first to fourth wavelengths will be focused on the first photosensitive cell 111, the second photosensitive cell 112, the third photosensitive cell 113, and the fourth photosensitive cell 114, respectively. In other words, the light that has passed through the color separation lens array 130 can be split into light beams according to wavelength, each beam traveling in a different direction and then being focused, thereby achieving the same optical effect.

In this way, a predetermined propagation distance requirement is set so that light of that wavelength can be focused onto that photosensitive cell, and the thickness h of the spacer layer 120 can be determined accordingly. The thickness h of the spacer layer 120 also depends on the wavelength λ to be split, the pixel size, and the arrangement pitch p of the photosensitive cells. The thickness h of the spacer layer 120 can be larger than the central wavelength λ of the visible light wavelength band to be split, and can be in the range of 1p to 3p compared to the arrangement pitch p of the photosensitive cells, which is the distance between the centers of adjacent photosensitive cells. Specifically, the thickness h of the spacer layer 120 can be in the range of 500 nm to 5 μm. Further details on setting the thickness h of the spacer layer 120 will be described later with reference to FIGS. 10A to 10E, 11A to 11E, and 12A to 12E.

Figures 6A and 6B are computer-generated images of the phase distribution of blue light passing through a color separation lens array and the focusing distribution of blue light in a photosensitive cell facing the color separation lens array. Figure 6C shows an example of a second region of the color separation lens array corresponding to blue pixel B and the direction of travel of blue light incident on its periphery. Figure 6D shows an example of a microlens array that acts equivalently to the color separation lens array with respect to blue light.

Regarding the phase distribution illustrated in Figure 6A, the phase at the center of the region corresponding to the blue pixel B is approximately 2π, the phase at the center of the region corresponding to the adjacent green pixel G exhibits a value of approximately π, and the phase at the center of the region corresponding to the diagonal red pixel R exhibits a value smaller than π (e.g., approximately 0.2π to 0.7π).

Such a phase distribution can exhibit a focusing distribution of blue light as shown in Figure 6B. Blue light is mostly focused in the area corresponding to blue pixel B, and almost no blue light reaches the areas corresponding to other pixels.

As a result, blue light incident on the second region 132 corresponding to the blue pixel B and its surrounding area passes through the color separation lens array 130 and then travels as shown in FIG. 6C . For example, of the incident light that is incident on the second region 132 of the color separation lens array 130 and part of the other regions surrounding the second region 132, the blue light is focused on the second photosensitive cell 112 immediately below the second region 132. In other words, incident on one blue pixel B are blue light from the second region 132 corresponding to that blue pixel B, blue light from two first regions 131 horizontally adjacent to the second region 132, blue light from two fourth regions 134 vertically adjacent to the second region 132, and blue light from four third regions 133 diagonally adjacent to the second region 132.

As shown in FIG. 6D , the color separation lens array 130 can perform a function equivalent to that of an array of multiple microlenses ML1 arranged around the second photosensitive cells 112 with respect to blue light. Each equivalent microlens ML1 is larger than its corresponding second photosensitive cell 112, so that it can focus not only the blue light incident on the region of the second photosensitive cell 112 but also the blue light incident on other regions surrounding the second photosensitive cell 112 onto the second photosensitive cell 112. For example, each microlens ML1 is about four times larger than the corresponding second photosensitive cell 112, and the four sides of each microlens ML1 are parallel to the four sides of the second photosensitive cell 112.

Figures 7A and 7B are computer-generated images of the phase distribution of green light passing through a color separation lens array and the focusing distribution of green light in photosensitive cells facing the color separation lens array. Figure 7C shows an example of the first and fourth regions of the color separation lens array corresponding to green pixels and the direction of travel of green light incident on their peripheries. Figure 7D shows an example of a microlens array that functions equivalently to the color separation lens array with respect to green light.

Referring to the phase distribution illustrated in Figure 7A, the phase at the center of the region corresponding to the green pixel G is approximately 2π, while the phase at the center of the regions corresponding to the adjacent blue pixel B and red pixel R exhibits a value of approximately π.

Such a phase distribution can exhibit a focusing distribution of green light as shown in Figure 7B. The green light is divided and focused in areas corresponding to two green pixels G, with very little green light reaching areas corresponding to other pixels.

As a result, the green light incident on the first region 131 and fourth region 134 corresponding to the green pixel G and their surroundings passes through the color separation lens array 130 and then travels as shown in FIG. 7C . For example, of the incident light that is incident on the first region 131 of the color separation lens array 130 and parts of the other regions surrounding the first region 131, the green light is focused on the first photosensitive cell 111 immediately below the first region 131. In other words, the green light incident on one green pixel G comes from the first region 131 or fourth region 134 corresponding to that green pixel G, and from two second regions 132 and two third regions 133 that are horizontally and vertically adjacent to the first region 131 or fourth region 134.

7D , for green light, the color separation lens array 130 can function equivalently to an array of microlenses ML2 arranged around the first and fourth photosensitive cells 111 and 114. Each equivalent microlens ML2 is larger than the corresponding first and fourth photosensitive cells 111 and 114, respectively, and can therefore focus not only the green light incident on the regions of the first and fourth photosensitive cells 111 and 114 but also the green light incident on other regions surrounding the first and fourth photosensitive cells 111 and 114 onto the first and fourth photosensitive cells 111 and 114. For example, each microlens ML2 is twice as large as the corresponding first or fourth photosensitive cell 111 or 114, and is disposed diagonally adjacent to the corresponding first or fourth photosensitive cell 111 or 114.

Figures 8A and 8B are computer-generated images of the phase distribution of red light passing through a color separation lens array and the focusing distribution of red light in photosensitive cells facing the color separation lens array. Figure 8C shows an example of a third region of the color separation lens array corresponding to a red pixel and the direction of travel of red light incident on its periphery. Figure 8D shows an example of a microlens array that functions equivalently to the color separation lens array with respect to the red pixel R.

Explaining the phase distribution illustrated in Figure 8A, the phase at the center of the region corresponding to the red pixel R is approximately 2π, the phase at the center of the region corresponding to the adjacent green pixel G exhibits a value of approximately π, and the phase at the center of the region corresponding to the diagonally opposite blue pixel B exhibits a value smaller than π (e.g., approximately 0.2π to 0.7π).

Such a phase distribution can exhibit a focusing distribution of red light as shown in Figure 8B. Red light is focused in the area corresponding to the red pixel R, and very little red light reaches the areas corresponding to other pixels.

As a result, light incident on the third region 133 corresponding to the red pixel R and its surrounding area passes through the color separation lens array 130 and then travels as shown in FIG. 8C . For example, of the incident light that is incident on the third region 133 of the color separation lens array 130 and on parts of the other regions surrounding the third region 133, red light is focused on the third photosensitive cell 113 immediately below the third region 133. In other words, incident on one red pixel R are the red light from the third region 133 corresponding to that red pixel R, the red light from two fourth regions 134 that are horizontally adjacent to the third region 133, the red light from two first regions 131 that are vertically adjacent to the third region 133, and the red light from four second regions 132 that are diagonally adjacent to the third region 133.

As shown in FIG. 8D , the color separation lens array 130 can perform a function equivalent to that of an array of multiple microlenses ML3 arranged around the third photosensitive cells 113, with respect to red light. Each equivalent microlens ML3 is larger than its corresponding third photosensitive cell 113, so that it can focus not only the red light incident on the region of the third photosensitive cell 113 but also the red light incident on other regions surrounding the third photosensitive cell 113 onto the third photosensitive cell 113. For example, each microlens ML3 is about four times larger than the corresponding third photosensitive cell 113, and the four sides of each microlens ML3 are parallel to the four sides of the third photosensitive cell 113.

The paths of blue light, green light, and red light described in Figures 6C, 7C, and 8C are forms in which light incident on each region is split according to color, and can also be described as follows:

9A exemplarily illustrates the traveling directions of light beams incident on a region corresponding to a blue pixel. Referring to FIG. 9A , among light beams _Li incident on the second region 132 corresponding to a blue pixel B, blue light beams Li _B travel toward the second photosensitive cell 112 located immediately below the second region 132. Among light beams _Li incident on the second region 132, green light beams Li _G travel mostly toward two first photosensitive cells 111 horizontally adjacent to the second photosensitive cell 112 and two fourth photosensitive cells 114 vertically adjacent to the second photosensitive cell 112. Among light beams _Li , red light beams Li _R travel mostly toward four third photosensitive cells 113 diagonally adjacent to the second photosensitive cell 112.

9B exemplarily illustrates the traveling directions of light beams incident on a region corresponding to a green pixel G. Referring to FIG. 9B, among the light beams L _i incident on the first region 131 corresponding to the green pixel G, green light beams L _G travel toward the first photosensitive cell 111 located immediately below the first region 131. Among the light beams L _i incident on the first region 131, blue light beams L _B travel toward two second photosensitive cells 112 adjacent to the first photosensitive cell 111 in the horizontal direction, and red light beams L _R travel toward two third photosensitive cells 113 adjacent to the first photosensitive cell 111 in the vertical direction.

9C exemplarily illustrates the traveling directions of light incident on a region corresponding to a red pixel. Of the light _Li incident on the third region 133 corresponding to the red pixel R, red light L _R travels toward the third photosensitive cell 113 located immediately below the third region 133. Of the incident light _Li incident on the third region 133, green light L _G travels toward two first photosensitive cells 111 vertically adjacent to the third photosensitive cell 113 and two fourth photosensitive cells 114 horizontally adjacent to the third photosensitive cell 113. Of the incident light _Li , blue light L _B travels mostly toward four second photosensitive cells 112 diagonally adjacent to the third photosensitive cell 113.

Such color separation and light collection can be achieved more effectively by appropriately setting the thickness of the spacer layer 120. For example, the theoretical thickness _ht of the spacer layer 120 can satisfy the following Equation 1, where n is the refractive index of the spacer layer 120 related to the wavelength _λ0 and p is the pitch of the photosensitive cells:

Here, the theoretical thickness _ht of the spacer layer 120 means the focal length at which light having a wavelength of _λ0 is focused onto the upper surfaces of the photosensitive cells 111, 112, 113, and 114 by the color separation lens array 130. In other words, the light having a wavelength of _λ0 is also focused at a distance of _ht from the lower surface of the color separation lens array 130 while passing through the color separation lens array 130.

As shown in Equation 1, the theoretical thickness _ht of the spacer layer 120 also depends on the pitch p of the photosensitive cells 111, 112, 113, and 114 and the refractive index n of the spacer layer 120. For example, assuming that the center wavelength _λ0 of the visible light band is 540 nm, the pitch p of the photosensitive cells 111, 112, 113, and 114 is 0.8 μm, and the refractive index n of the spacer layer 120 at a wavelength of 540 nm is 1.46, the theoretical thickness _ht of the spacer layer 120, in other words, the optimal distance between the lower surface of the color separation lens array 130 and the upper surface of the sensor substrate 110, is approximately 1.64 μm. However, the actual thickness of the spacer layer 120 does not need to be limited to the theoretical thickness _ht shown in Equation 1. For example, the actual thickness of the spacer layer 120 may be selected within a predetermined range based on the theoretical thickness _ht of Equation 1, taking into account the efficiency of the color separation lens array 130.

Figures 10A to 10E are graphs illustrating exemplary changes in the efficiency of the color separation lens array 130 depending on the distance between the color separation lens array 130 and the sensor substrate 110 when the pitch of the photosensitive cells 111, 112, 113, and 114 is 0.7 μm. FIG. 10A shows the light-collecting efficiency of the color separation lens array 130 with respect to blue light incident on the second photosensitive cell 112 from the first region 131 to the fourth region 134 constituting the unit pattern array of the color separation lens array 130. FIG. 10B shows the light-collecting efficiency of the color separation lens array 130 with respect to green light incident on the first photosensitive cell 111 and the fourth photosensitive cell 114 from the first region 131 to the fourth region 134 constituting the unit pattern array. FIG. 10C shows the light-collecting efficiency of the color separation lens array 130 with respect to red light incident on the third photosensitive cell 113 from the first region 131 to the fourth region 134 constituting the unit pattern array.

10A and 10C, four regions are arranged for one photosensitive cell, so the theoretical maximum value is 4. In the case of Fig. 10B, four regions are arranged for two photosensitive cells, so the theoretical maximum value is 2. In the graphs of Fig. 10A to 10C, the distance at which the light collection efficiency of the color separation lens array 130 is highest is the theoretical thickness _ht that satisfies Equation 1. As shown in Fig. 10A to 10C, the theoretical thickness _ht varies slightly depending on the wavelength.

Figure 10D is a graph showing an example of the change in efficiency of a color separation lens array taking into account the sensitivity characteristics of the human eye to visible light. For example, the human eye is generally most sensitive to green light and least sensitive to blue light. Therefore, the graph of Figure 10D can be obtained by assigning the lowest weighting to the graph of Figure 10A, a weighting higher than blue light to the graph of Figure 10C, and the highest weighting to Figure 10B, and then averaging the combined values. Figure 10E is a graph showing the results of normalizing the graph of Figure 10D.

Referring to the graphs of FIGS. 10D and 10E, when the pitch of the photosensitive cells 111, 112, 113, and 114 is 0.7 μm, the efficiency of the color separation lens array 130 with respect to the entire visible light spectrum, taking into account the sensitivity characteristics of the human eye, is highest at a distance of about 1.2 μm. Furthermore, the efficiency of the color separation lens array 130 is approximately 80% of its maximum efficiency at a distance of about 0.5 μm, and approximately 95% of its maximum efficiency at a distance of about 1.9 μm.

11A to 11E are graphs showing an example of how the efficiency of the color separation lens array 130 varies with the distance between the color separation lens array 130 and the sensor substrate 110 when the pitch of the photosensitive cells 111, 112, 113, and 114 is 0.8 μm. Referring to FIGS. 11A to 11E, when the pitch of the photosensitive cells 111, 112, 113, and 114 is 0.8 μm, the efficiency of the color separation lens array 130 with respect to all visible light rays, taking into account the sensitivity characteristics of the human eye, is highest at a distance of about 1.64 μm. In addition, the efficiency of the color separation lens array 130 is approximately 85% of its maximum efficiency at a distance of about 0.8 μm, and approximately 93% of its maximum efficiency at a distance of about 2.5 μm.

12A to 12E are graphs showing an example of how the efficiency of the color separation lens array 130 varies with the distance between the color separation lens array 130 and the sensor substrate 110 when the pitch of the photosensitive cells 111, 112, 113, and 114 is 1.0 μm. Referring to FIGS. 12A to 12E, when the pitch of the photosensitive cells 111, 112, 113, and 114 is 1.0 μm, the efficiency of the color separation lens array 130 with respect to all visible light rays, taking into account the sensitivity characteristics of the human eye, is highest at a distance of about 2.6 μm. Furthermore, the efficiency of the color separation lens array 130 is approximately 87% of its maximum efficiency at a distance of about 1.6 μm, and approximately 94% of its maximum efficiency at a distance of about 3.6 μm.

As a result, it can be seen that the color separation lens array 130 has a high efficiency of 80% or more, 90% or more, or 95% or more of the maximum efficiency even if the actual thickness _h of the spacer layer 120 is larger or smaller than the theoretical thickness ht of Equation 1 by the pitch p of the photosensitive cells 111, 112, 113, and 114. Considering the above results, the actual thickness h of the spacer layer 120 can also be selected within the range of ht- _p ≦h≦ _ht +p.

The color separation lens array 130 described above splits incident light into wavelengths without absorbing or blocking it, and focuses the split light on specific areas, thereby improving the light utilization efficiency of the image sensor. Furthermore, because the color separation lens array 130 has improved color separation performance, an image sensor employing the color separation lens array 130 can have excellent color purity. Furthermore, an image sensor employing the color separation lens array 130 can maintain the Bayer pattern method commonly adopted in image sensors, and can utilize the same image processing algorithm as the existing pixel structure. Furthermore, because the color separation lens array 130 can also function as a lens that focuses incident light, an image sensor employing the color separation lens array 130 does not require a separate microlens to focus light on each pixel.

Figure 13 is a perspective view showing an exemplary shape of a nanopost that may also be used in a color separation lens array according to one embodiment. Referring to Figure 13, the nanopost may have a cylindrical shape with a diameter D and a height H. The diameter D and/or height H may have sub-wavelength values, and the diameter D may vary depending on the location where the nanopost is disposed.

The nanoposts can also be formed into pillars with various cross-sectional shapes. Figures 14A to 14H are plan views showing exemplary shapes of nanoposts that can be used in the color separation lens array 130 of the image sensor.

The cross-sectional shape of the nanopost can be a circular ring shape with an outer diameter D and an inner diameter Di, as shown in Figure 14A. The ring width w can have a sub-wavelength value. The cross-sectional shape of the nanopost can be an ellipse shape with different major axis lengths Dx and minor axis lengths Dy in the first direction (X direction) and second direction (Y direction), as shown in Figure 14B. Such a shape is also adopted for the first region 131 and fourth region 134 corresponding to the green pixel, as mentioned when describing the embodiment of Figure 5B.

Furthermore, the cross-sectional shape of the nanopost can be a square, a square ring, or a cross, as shown in Figures 14C, 14D, and 14F, or a rectangular or cross shape with different lengths Dx and Dy in the first direction (X direction) and the second direction (Y direction), as shown in Figures 14E and 14G. Such rectangular or cross shapes are also used for the first region 131 and the fourth region 134 corresponding to the green pixel, as mentioned when describing the embodiment of Figure 5B.

As yet another example, the cross-sectional shape of the nanopost may have multiple concave arcs, as shown in Figure 14H.

Figure 15 is a plan view illustrating an exemplary arrangement of nanoposts forming a color separation lens array according to another embodiment.

The color separation lens array 140 corresponds to the Bayer pattern pixel array illustrated in FIG. 2A and may include a region divided into four regions: a first region 141 corresponding to a green pixel G, a second region 142 corresponding to a blue pixel B, a third region 143 corresponding to a red pixel R, and a fourth region 144 corresponding to a green pixel G. Although not shown, such unit pattern arrays may be arranged repeatedly along the first direction (X direction) and the second direction (Y direction). Each region may be equally divided into multiple subregions, and nanoposts NPs may be arranged at the intersections of the subregion boundaries. FIG. 15 shows an example with nine subregions, with nanoposts NPs arranged at the lattice points dividing the nine subregions. Each region (141, 142, 143, 144) has no nanopost NPs in the center, but instead has four nanoposts NPs of the same size forming a central area. The peripheral nanoposts NPs are arranged along the boundaries of other regions. The nanoposts NPs are labeled r1 to r9 according to their detailed positions within the unit pattern array.

Referring to FIG. 15, nanopost r1 located at the center of first region 141 corresponding to a green pixel has a larger cross-sectional area than nanoposts r5, r6, and r9 located at the periphery, and nanopost r4 located at the center of fourth region 144 corresponding to a green pixel also has a larger cross-sectional area than nanoposts r7, r8, and r9 located at the periphery. The cross-sectional sizes of nanoposts r1 and r4 located at the centers of first region 141 and fourth region 144 corresponding to a green pixel are also larger than the cross-sectional sizes of nanopost r2 located at the center of second region 142 corresponding to a blue pixel and nanopost r3 located at the center of third region 143 corresponding to a red pixel. The cross-sectional area of nanopost r2 located at the center of second region 142 corresponding to a blue pixel is also larger than the cross-sectional area of nanopost r3 located at the center of third region 143 corresponding to a red pixel.

The nanoposts NP in the second region 142 and the third region 143 are also arranged symmetrically along the first direction (X direction) and the second direction (Y direction), while the nanoposts NP in the first region 141 and the fourth region 144 are also arranged asymmetrically along the first direction (X direction) and the second direction (Y direction). In other words, the nanoposts NP in the second region 142 and the third region 143, which correspond to blue and red pixels, respectively, can have the same distribution pattern along the first direction (X direction) and the second direction (Y direction), while the nanoposts NP in the first region 141 and the fourth region 144, which correspond to green pixels, can have different distribution patterns along the first direction (X direction) and the second direction (Y direction).

Of the nanoposts NP, the cross-sectional area of nanopost r5 located at the boundary between the first region 141 and the second region 142 adjacent to it in the first direction (X direction) is different from the cross-sectional area of nanopost r6 located at the boundary between the first region 141 and the third region 143 adjacent to it in the second direction (Y direction). Furthermore, the cross-sectional area of nanopost r7 located at the boundary between the fourth region 144 and the third region 143 adjacent to it in the first direction (X direction) is different from the cross-sectional area of nanopost r8 located at the boundary between the fourth region 144 and the second region 142 adjacent to it in the second direction (Y direction).

On the other hand, the cross-sectional area of nanopost r5 located at the boundary between the first region 141 and the second region 142 adjacent to it in the first direction (X direction) is the same as the cross-sectional area of nanopost r8 located at the boundary between the fourth region 144 and the second region 142 adjacent to it in the second direction (Y direction), and the cross-sectional area of nanopost r6 located at the boundary between the first region 141 and the third region 143 adjacent to it in the second direction (Y direction) is the same as the cross-sectional area of nanopost r7 located at the boundary between the fourth region 144 and the third region 143 adjacent to it in the first direction (X direction).

On the other hand, nanopost r9 located at the corners of the first region 141, second region 142, third region 143, and fourth region 144, i.e., at the intersections of the four regions, has the same cross-sectional area.

In this way, in the second region 142 and the third region 143, which correspond to the blue pixel and the red pixel, respectively, the nanoposts NPs are arranged in a four-fold symmetrical form, while in the first and fourth regions 141 and 144, which correspond to the green pixel, the nanoposts NPs are arranged in a two-fold symmetrical form, with the first region 141 and the fourth region 144 rotated 90° relative to each other. Such a form is also shown in the embodiments of Figures 16 and 17, which will be described later.

Figure 16 is a plan view illustrating an exemplary arrangement of nanoposts forming a color separation lens array according to yet another embodiment.

The color separation lens array 150 has a shape corresponding to a Bayer pattern pixel array and may include a region divided into four regions: a first region 151 corresponding to green pixels, a second region 152 corresponding to blue pixels, a third region 153 corresponding to red pixels, and a fourth region 154 corresponding to green pixels. Each region may be equally divided into multiple subregions, and nanoposts NPs may be placed at the intersections of the subregion boundaries. Figure 16 differs from the nanopost array of Figure 15 in that it shows an example with 16 subregions. Nanoposts NPs are placed on lattice points dividing the 16 subregions, with a nanopost NP located in the center of each region 151, 152, 153, and 154. The nanopost NPs are labeled s1 to s11 according to their precise position within the unit pattern array.

In the embodiment of FIG. 16, the nanopost s1 located in the center of the first region 151 corresponding to the green pixel and the nanopost s4 located in the center of the fourth region 154 not only have a larger cross-sectional area than the nanoposts NP located on the periphery, but also have a larger cross-sectional area than the nanoposts NP located in the second region 152 corresponding to the blue pixel and the third region 153 corresponding to the red pixel.

In the first region 151, nanopost s1, which has the largest cross-sectional area, is located in the center, followed by nanoposts s10, s5, and s6, whose cross-sectional areas gradually decrease toward the periphery. In the fourth region 154, nanopost s4, which has the largest cross-sectional area, is located in the center, followed by nanoposts s11, s7, and s8, whose cross-sectional areas gradually decrease toward the periphery. In contrast, in the second region 152, nine nanoposts s2, each with the same cross-sectional area, are located in the center, followed by nanoposts s5 and s8, each with a larger cross-sectional area, located on the periphery. In the third region 153, nine nanoposts s3, each with the same cross-sectional area, are located in the center, followed by nanoposts s6 and s7, whose cross-sectional areas gradually decrease toward the periphery. In both the second region 152 and the third region 153, the nanoposts NP in the peripheral regions are arranged on the boundary lines with the other regions.

In the embodiment of Figure 16, as in the embodiment of Figure 15, the nanoposts NP in the second region 152 and the third region 153 are also arranged symmetrically along the first direction (X direction) and the second direction (Y direction), and the nanoposts NP in the first region 151 and the fourth region 154 are also arranged asymmetrically along the first direction (X direction) and the second direction (Y direction). Furthermore, the nanoposts s9 arranged at the corners of the first region 151, the second region 152, the third region 153, and the fourth region 154, i.e., at positions where the four regions are adjacent, have the same cross-sectional area.

Figure 17 is a plan view illustrating an exemplary arrangement of nanoposts forming a color separation lens array according to yet another embodiment.

The color separation lens array 160 has a shape corresponding to the pixel arrangement of a Bayer pattern and may include a region divided into four regions: a first region 161 corresponding to green pixels, a second region 162 corresponding to blue pixels, a third region 163 corresponding to red pixels, and a fourth region 164 corresponding to green pixels. Each region may be equally divided into multiple subregions, and nanoposts NPs may be arranged within the subregions. Similar to FIG. 15, the color separation lens array 160 is divided into nine subregions, but differs in that the nanoposts NPs are arranged inside the subregions, not at their intersections. The nanoposts NPs are labeled t1 to t16 according to their precise position within the unit pattern array.

In the embodiment of FIG. 17, nanopost t1 located at the center of first region 161 and nanopost t4 located at the center of fourth region 164 have larger cross-sectional areas than not only the nanoposts NP located in their peripheral regions but also the nanoposts NP located in the second and third regions 162 and 163. The cross-sectional area of nanopost t2 located at the center of second region 162 is also larger than the cross-sectional area of nanopost t3 located at the center of third region 163. In the case of second region 162, the cross-sectional areas of nanoposts t6 and t10 located in the peripheral regions spaced apart from the center in the first direction (X direction) and the second direction (Y direction) are larger than the cross-sectional area of central nanopost t2. In contrast, the cross-sectional area of nanopost t14 located in the peripheral region spaced apart from the center in the diagonal direction is smaller than the cross-sectional area of central nanopost t2. In the third region 163, the central nanopost t3 has the smallest cross-sectional area, and the peripheral nanoposts t7, t11, and t15 all have larger cross-sectional areas than the central nanopost t3.

The nanoposts NP in the second region 162 and the third region 163 are arranged symmetrically along the first direction (X direction) and the second direction (Y direction), while the nanoposts NP in the first region 161 and the fourth region 164 are arranged asymmetrically along the first direction (X direction) and the second direction (Y direction). In other words, the nanoposts NP in the second region 162 and the third region 163, which correspond to blue and red pixels, respectively, exhibit the same distribution pattern along the first direction (X direction) and the second direction (Y direction), while the nanoposts NP in the first region 161 and the fourth region 164, which correspond to green pixels, exhibit different distribution patterns along the first direction (X direction) and the second direction (Y direction).

In the first region 161, the central nanopost t1, the nanopost t5 adjacent to it in the first direction (X direction), and the nanopost t9 adjacent to it in the second direction (Y direction) have different cross-sectional areas. In the fourth region 164, the central nanopost t4, the nanopost t8 adjacent to it in the first direction (X direction), and the nanopost t12 adjacent to it in the second direction (Y direction) also have different cross-sectional areas. In this case, nanopost t1 at the center of first region 161 and nanopost t5 adjacent to it in the first direction (X direction) have the same cross-sectional area, as do nanopost t4 at the center of fourth region 164 and nanopost t12 adjacent to it in the second direction (Y direction). Nanopost t1 at the center of first region 161 and nanopost t9 adjacent to it in the second direction (Y direction) have the same cross-sectional area, as do nanopost t4 at the center of fourth region 164 and nanopost t8 adjacent to it in the first direction (X direction). Nanopost t13 adjacent to the corner of first region 161 and nanopost t16 adjacent to the corner of fourth region 164 have the same cross-sectional area. In this way, first region 161 and fourth region 164 are rotated 90° relative to each other.

Nanopost t2 at the center of second region 162, nanopost t6 adjacent to it in the first direction (X direction), and nanopost t10 adjacent to it in the second direction (Y direction) all have the same cross-sectional area. Nanopost t14 located adjacent to the corner of second region 162 also has the same cross-sectional area.

In the third region 163, the central nanopost t3, the nanopost t7 adjacent to it in the first direction (X direction), and the nanopost t11 adjacent to it in the second direction (Y direction) all have the same cross-sectional area. Nanopost t15 located adjacent to the corner of the third region 163 also has the same cross-sectional area.

Figure 18 is a plan view illustrating an exemplary arrangement of multiple nanoposts forming a color separation lens array according to yet another embodiment.

The color separation lens array 170 of Figure 18 is an embodiment with the simplest structure. One nanopost NP is arranged in each of the first region 171 corresponding to the green pixel, the second region 172 corresponding to the blue pixel, the third region 173 corresponding to the red pixel, and the fourth region 174 corresponding to the green pixel. The cross-sectional areas of the nanopost NPs provided in the first region 171 and the fourth region 174 are the largest, the cross-sectional area of the nanopost NPs provided in the second region 172 is smaller than the cross-sectional area of the nanopost NPs provided in the first region 171, and the cross-sectional area of the nanopost NPs in the third region 173 is the smallest.

Figure 19 is a graph showing an example of the spectral distribution of light incident on each of the red pixels R, green pixels G, and blue pixels B of an image sensor including the color separation lens array of Figure 18.

Figures 20A and 20B are cross-sectional views showing the schematic structure of a pixel array according to another embodiment, each taken at a different cross section. The pixel array 1100a differs from the embodiment shown in Figures 4A and 4B in that a color filter 105 is further disposed between the sensor substrate 110 and the color separation lens array 130. The color filter 105 is also disposed between the sensor substrate 110 and the spacer layer 120.

The pixel array 1100a may further include a transparent dielectric layer 121 that protects the color separation lens array 130. The dielectric layer 121 is also disposed to cover the spaces between adjacent nanopost NPs and the top surfaces of the nanopost NPs. The dielectric layer 121 may be made of a material having a refractive index lower than that of the nanopost NPs, for example, the same material as the spacer layer 120.

The color filter 105 has filter regions whose shape corresponds to the pixel arrangement of the Bayer pattern. As shown in FIG. 20A, green filter regions CF1 and blue filter regions CF2 are alternately arranged, and as shown in FIG. 20B, red filter regions CF3 and green filter regions CF1 are alternately arranged in rows spaced apart in the Y direction. The color filter 105 is not an essential component, since the color separation lens array 130 splits and focuses light of different wavelengths onto the multiple photosensitive cells 111, 112, 113, and 114. However, the additional color filter 105 complements color purity, and since light that is significantly color-separated enters the color filter 105, light loss is not significant.

Figures 21 and 22 are graphs showing exemplary spectral distributions of light incident on the red pixel R, green pixel G, and blue pixel B of the image sensor, respectively showing the spectral distributions of an embodiment with a color filter and an embodiment without a color filter.

The graph in Figure 21 shows the spectrum of an image sensor equipped with the color filters shown in Figures 20A and 20B, and the graph in Figure 22 shows the spectrum of an image sensor without the color filters shown in Figures 4A and 4B. Figures 21 and 22 are simulation results for an image sensor with a pixel width of approximately 0.7 μm. When color filters are provided, the overall amount of light tends to be lower, but both show good color separation performance.

FIG. 23 is a plan view illustrating an example of a color separation lens array according to another embodiment. Referring to FIG. 23, the color separation lens array 340 may include a number of unit pattern arrays indicated by thick lines. Each unit pattern array is also arranged in a 2x2 two-dimensional form including a first region 341, a second region 342, a third region 343, and a fourth region 344. Looking at the overall configuration of the color separation lens array 340, the first regions 341 and the second regions 342 are alternately arranged in the horizontal direction within one row, and the third regions 343 and the fourth regions 344 are alternately arranged in the horizontal direction within another row. Furthermore, the first regions 341 and the third regions 343 are alternately arranged in the vertical direction within one column, and a number of second regions 342 and a number of fourth regions 344 are alternately arranged in the vertical direction within another column.

The color separation lens array 340 may further include a plurality of first regions 341 to 344 that do not belong to any unit pattern array. The first regions 341 to 344 that do not belong to any unit pattern array may also be arranged along the edge of the color separation lens array 340. In other words, a plurality of second regions 342 and a plurality of fourth regions 344 may be additionally arranged in a row at the left edge of the color separation lens array 340, a plurality of first regions 341 and a plurality of third regions 343 may be additionally arranged in a row at the right edge, a plurality of third regions 343 and a plurality of fourth regions 344 may be additionally arranged in a row at the upper edge, and a plurality of first regions 341 and a plurality of second regions 342 may be additionally arranged in a row at the lower edge.

24 is a vertical cross-section of the color separation lens array 340 shown in FIG. 23 taken along line C-C'. Referring to FIG. 24, the color separation lens array 340 may include a plurality of first regions 341 and a plurality of second regions 342 that are arranged to protrude horizontally from the edge of the sensor substrate 110 and do not face any photosensitive cells of the sensor substrate 110 in the vertical direction. Although not shown in FIG. 24, the plurality of first regions 341 to fourth regions 344 that do not belong to any unit pattern array in FIG. 23 are all arranged to protrude horizontally from the edge of the sensor substrate 110 and do not face any photosensitive cells in the vertical direction.

As described with reference to FIGS. 6A to 6D, 7A to 7D, and 8A to 8D, each photosensitive cell receives light not only from the region of the color separation lens array 340 that corresponds to it in the vertical direction, but also from numerous other regions located around that region. Therefore, without the first to fourth regions 341 to 344 added along the edge of the color separation lens array 340, the amount of light incident on the photosensitive cells arranged along the edge of the sensor substrate 110 would be reduced, resulting in a decrease in color purity. By adding the first to fourth regions 341 to 344 along the edge of the color separation lens array 340, light can be provided to the photosensitive cells arranged along the edge of the sensor substrate 110 in the same way as the photosensitive cells arranged inside the sensor substrate 110. The embodiments illustrated in FIGS. 23 and 24 may also be applied to the color separation lens arrays 130, 140, 150, 160, and 170 described above.

Figure 25 is a cross-sectional view showing the schematic structure of a pixel array according to yet another embodiment, and Figure 26 is a perspective view showing an exemplary shape of nanoposts used in the color separation lens array of Figure 25.

The pixel array 1100b includes a sensor substrate 310 that senses light and a color separation lens array 350 disposed on the sensor substrate 310. A spacer layer 320 is disposed between the sensor substrate 310 and the color separation lens array 350. The color separation lens array 350 is supported by the spacer layer 320 and includes a plurality of nanoposts NPs arranged according to a predetermined pattern. The sensor substrate 310 includes a plurality of photosensitive cells that sense light, and can face the plurality of regions of the color separation lens array 350 in one-to-one correspondence. The illustration of such region divisions has been omitted for convenience.

The color separation lens array 350 of this embodiment differs from the previously described embodiment in that each of the multiple nanoposts NP includes a lower post LP and an upper post UP stacked on the lower post LP.

Some of the nanoposts NP may have a stacked shape in which the lower posts LP and upper posts UP are misaligned with each other. The degree of misalignment is indicated by b in FIG. 26, and this magnitude increases as one moves from the center C to the periphery p of the pixel array 1100b, i.e., in the radial direction. The direction in which the upper posts UP are misaligned from the lower posts LP is from the center C toward the periphery p.

To fabricate nanoposts NP with such a structure, a first material layer 331 that fills the area between the lower posts LP and supports the upper posts UP, and a second material layer 332 that covers the upper posts UP may be further provided. The first material layer 331 and the second material layer 332 may be formed of a material with a refractive index lower than that of the material forming the upper posts UP and lower posts LP.

This arrangement takes into account the fact that the angle of light incidence differs between the periphery and center of the pixel array 1100b used in the imaging device. Generally, light is incident perpendicularly near the center C of the pixel array 1100b, and the angle of incidence increases as it approaches the periphery p. By configuring the nanopost NP in a form that corresponds to this incidence path, it is possible to more effectively achieve the color separation intended by the nanopost NP, even for oblique light rays that are incident obliquely on the pixel array 1100b.

Although the nanopost NPs are illustrated as having a two-layer structure, they can also have a three-layer or more structure, and the shape and size of the nanoposts in the two layers can vary depending on their position. The embodiments shown in Figures 25 and 26 can also be applied to the color separation lens arrays 130, 140, 150, 160, 170, and 340 described above.

Because the image sensor according to the above-described embodiment suffers almost no light loss due to the color filter, it can provide a sufficient amount of light to each pixel even when the pixel size is small. Therefore, it is possible to fabricate ultra-high-resolution, micro-high-sensitivity image sensors with hundreds of millions of pixels. Such ultra-high-resolution, micro-high-sensitivity image sensors can also be used in a variety of high-performance optical or electronic devices. Examples of such electronic devices include, but are not limited to, smartphones, mobile phones, cell phones, PDAs (personal digital assistants), laptops, PCs (personal computers), various portable devices, home appliances, security cameras, medical cameras, automobiles, Internet of Things (IoT) devices, and other mobile or non-mobile computing devices.

Figure 27 is a block diagram illustrating an electronic device including an image sensor according to one embodiment. The electronic device includes an image sensor 1000, a processor 2200, a memory 2300, a display 2400, and a bus 2500. The image sensor 1000 acquires image information related to an external object under the control of the processor 2200 and provides it to the processor 2200. The processor 2200 can store the image information provided from the image sensor 1000 in the memory 2300 via the bus 2500 and output the image information stored in the memory 2300 to the display 2400 for display to the user. The processor 2200 can also perform various image processing on the image information provided from the image sensor 1000.

Figures 28 to 38 show various multimedia examples of electronic devices to which an image sensor according to one embodiment is applied.

An image sensor according to one embodiment can also be applied to various multimedia devices equipped with video capture capabilities. For example, the image sensor can also be applied to the camera 2000 shown in FIG. 28. The camera 2000 can also be a digital camera or a digital camcorder.

Referring to FIG. 29, the camera 2000 may include an imaging unit 2100, an image sensor 1000, and a processor 2200.

The imaging unit 2100 focuses light reflected from the object OBJ to form an optical image. The imaging unit 2100 may include an objective lens 2010, a lens driver 2120, an aperture 2130, and an aperture driver 2140. For convenience, only one lens is shown in FIG. 29 ; however, in reality, the objective lens 2010 may include multiple lenses of different sizes and shapes. The lens driver 2120 may communicate information related to focus detection with the processor 2200 and adjust the position of the objective lens 2010 based on a control signal provided by the processor 2200. The lens driver 2120 may move the objective lens 2010 to adjust the distance between the objective lens 2010 and the object OBJ or adjust the position of individual lenses within the objective lens 2010. The lens driver 2120 may drive the objective lens 2010 to adjust the focus on the object OBJ. Such a camera 2000 may be equipped with an auto focus (AF) function.

The aperture driver 2140 can communicate information related to the amount of light with the processor 2200 and adjust the aperture 2130 based on a control signal provided by the processor 2200. For example, the aperture driver 2140 can increase or decrease the aperture of the aperture 2130 and adjust the opening time of the aperture 2130 depending on the amount of light entering the camera 2000 through the objective lens 2010.

The image sensor 1000 can generate an electrical image signal based on the intensity of incident light. The image sensor 1000 may include a pixel array 1100, a timing controller (T/C) 1010, and an output circuit 1030. Although not shown in FIG. 29, the image sensor 1000 may further include a row decoder as shown in FIG. 1. Light passing through the objective lens 2010 and the aperture 2130 can form an image of the object OBJ on the light-receiving surface of the pixel array 1100. The pixel array 1100 may be a CCD or CMOS that converts optical signals into electrical signals. The pixel array 1100 may include additional pixels for performing an autofocus (AF) function or a distance measurement function. The pixel array 1100 may also include the color separation lens array described above.

The processor 2200 can control the overall operation of the camera 2000 and can have image processing functions. For example, the processor 2200 can provide control signals for the operation of each component to the lens driver 2120, aperture driver 2140, timing controller 1010, etc.

An image sensor according to an embodiment may also be applied to a mobile phone or smartphone 3000 shown in FIG. 30, a tablet or smart tablet 3100 shown in FIG. 31, a laptop computer 3200 shown in FIG. 32, or a television or smart TV 3300 shown in FIG. 33. For example, the smartphone 3000 or smart tablet 3100 may include multiple high-resolution cameras, each equipped with a high-resolution image sensor. The high-resolution cameras may be used to extract depth information of an object in an image, adjust out-of-focus of the image, or automatically identify an object in an image.

Image sensors are also applied to the smart refrigerator 3400 shown in FIG. 34, the security camera 3500 shown in FIG. 35, the robot 3600 shown in FIG. 36, and the medical camera 3700 shown in FIG. 35. For example, the smart refrigerator 3400 can automatically recognize food and beverages in the refrigerator using an image sensor and notify the user via a smartphone of the presence or absence of specific food and beverages, the type of food and beverages that have been taken in and out, etc. The security camera 3500 can provide ultra-high resolution images and uses high sensitivity to recognize objects or people in images even in dark environments. The robot 3600 can be deployed in disaster sites or industrial sites where people cannot directly approach and can provide high-resolution images. The medical camera 3700 can provide high-resolution images for diagnosis or surgery and can dynamically adjust its field of view.

The image sensor may also be applied to a vehicle 3800, as shown in FIG. 38. The vehicle 3800 may include a plurality of vehicle cameras 3810, 3820, 3830, and 3840 arranged at various positions. Each of the vehicle cameras 3810, 3820, 3830, and 3840 may include an image sensor according to an embodiment. The vehicle 3800 may use the plurality of vehicle cameras 3810, 3820, 3830, and 3840 to provide the driver with various information related to the interior or surroundings of the vehicle 3800, and may automatically recognize objects or people in the image and provide information necessary for autonomous driving.

Although the image sensor having the color separation lens array and the electronic device including the same have been described with reference to the embodiments illustrated in the drawings, these are merely exemplary, and those skilled in the art will understand that numerous modifications and equivalent embodiments are possible. Therefore, the disclosed embodiments should be considered from an illustrative rather than a restrictive perspective. The scope of the claims is set forth in the appended claims, not the foregoing description, and all differences that fall within the range of equivalents thereof should be construed as being within the scope of the claims.

105 color filter 110 sensor substrate 111, 112, 113, 114 photosensitive cell 120 spacer layer 130, 140, 150, 160, 170, 340, 350 color separation lens array 131, 141, 151, 161, 171 first region 132, 142, 152, 162, 172 second region 133, 143, 153, 163, 173 third region 134, 144, 154, 164, 174 fourth region 1000 image sensor 1010 timing controller 1020 row decoder 1030 output circuit 1100, 1100a, 1100b pixel array NP nanopost

Claims (20)

a sensor substrate including first and second photosensitive cells that detect light; and a color separation lens array including a first region facing the first photosensitive cells and including first nanoposts, and a second region facing the second photosensitive cells and including second nanoposts,
The first nanoposts and the second nanoposts are different from each other in at least one of shape, size, and arrangement;
the first nanoposts and the second nanoposts split light having a first wavelength and light having a second wavelength, which are different from each other, from the light incident on the color separation lens array into light beams in different directions, and form phase distributions at positions where the light beams pass through the first region and the second region and are focused on the first photosensitive cell and the second photosensitive cell, respectively;
the color separation lens array functions equivalently to an array of a plurality of microlenses for the light of the second wavelength, and each microlens is larger than the second photosensitive cell;
the color separation lens array functions equivalently to an array of a plurality of microlenses for the light of the first wavelength, and each microlens is larger than the first photosensitive cell;
The first nanopost and the second nanopost are
the light of the first wavelength forms a phase distribution of 2Nπ at a position corresponding to a center of the first photosensitive cell immediately after passing through the color separation lens array, and forms a phase distribution of (2N−1)π at a position corresponding to a center of the second photosensitive cell, where N is an integer greater than 0 . The first nanopost and the second nanopost are
2. The image sensor of claim 1, wherein, immediately after passing through the color separation lens array, the light of the second wavelength forms a phase distribution of (2M−1)π at a position corresponding to a center of the first photosensitive cell, and forms a phase distribution of 2Mπ at a position corresponding to a center of the second photosensitive cell, where M is an integer greater than 0. The image sensor according to claim 1 , further comprising a spacer layer disposed between the sensor substrate and the color separation lens array, forming a distance between the sensor substrate and the color separation lens array. The image sensor of claim 3 , wherein the spacer layer has a thickness corresponding to a focal length of the color separation lens array at a center wavelength of a wavelength band of incident light that is color-separated by the color separation lens array. Let h _t be the theoretical thickness of the spacer layer, p be the pitch between the photosensitive cells, n be the refractive index of the spacer layer, and λ ₀ be the central wavelength of the wavelength band of light that is color-separated by the color separation lens array. Then, the theoretical thickness h _t of the spacer layer is given by
and
4. The image sensor of claim 3 , wherein the spacer layer has an actual thickness h such that h _t -p≦h≦h _t +p. the sensor substrate further includes a third photo-sensitive cell and a fourth photo-sensitive cell that sense light,
the color separation lens array includes a third region facing the third photosensitive cell and including third nanoposts, and a fourth region facing the fourth photosensitive cell and including fourth nanoposts;
The image sensor of claim 1 , wherein the third nanoposts and the fourth nanoposts are different from each other in at least one of shape, size, and arrangement. 7. The image sensor of claim 6, wherein the first to fourth nanoposts split light beams of different first, second, and third wavelengths, which are incident on the color separation lens array, into different directions, and form a phase distribution at a position where the light beams pass through the first to fourth regions, such that the light beams of the first wavelength are focused on the first and fourth photosensitive cells, the light beams of the second wavelength are focused on the second photosensitive cells, and the light beams of the third wavelength are focused on the third photosensitive cells. 8. The image sensor of claim 7 , wherein the first wavelength is green light, the second wavelength is blue light, and the third wavelength is red light. The first nanopost to the fourth nanopost are
7. The image sensor according to claim 6, wherein, immediately after passing through the color separation lens array, the light of the first wavelength forms a phase distribution of 2Nπ at positions corresponding to the central parts of the first photosensitive cells and the fourth photosensitive cells, and forms a phase distribution of (2N−1)π at positions corresponding to the central parts of the second photosensitive cells and the third photosensitive cells, where N is an integer greater than 0. The first nanopost to the fourth nanopost are
10. The image sensor of claim 9, wherein, immediately after passing through the color separation lens array, the light of the second wavelength forms a phase distribution of (2M−1)π at positions corresponding to the central parts of the first photosensitive cells and the fourth photosensitive cells, a phase distribution of 2Mπ at a position corresponding to the central part of the second photosensitive cells, and a phase distribution larger than (2M−2)π and smaller than (2M−1)π at a position corresponding to the central part of the third photosensitive cell, where M is an integer larger than 0. The first nanopost to the fourth nanopost are
11. The image sensor according to claim 10, wherein, immediately after passing through the color separation lens array, the light of the third wavelength forms a phase distribution of (2L-1)π at positions corresponding to the central parts of the first and fourth photosensitive cells, a phase distribution of 2Lπ at a position corresponding to the central part of the third photosensitive cell, and a phase distribution larger than (2L-2)π and smaller than (2L-1)π at a position corresponding to the central part of the second photosensitive cell, where L is an integer larger than 0. the image sensor has a pixel array structure in which a plurality of unit pixels including red pixels, green pixels, and blue pixels are arranged in a Bayer pattern;
The image sensor of any one of claims 9 to 11, wherein the nanoposts provided in the regions corresponding to green pixels in the first to fourth regions have different distribution patterns along a first direction and a second direction perpendicular to the first direction. 13. The image sensor of claim 12, wherein the nanoposts provided in the regions corresponding to blue and red pixels in the first to fourth regions have a symmetrical distribution pattern along the first direction and the second direction. 13. The image sensor of claim 12, wherein in the first to fourth regions, the nanoposts located at the center of the region corresponding to the green pixel have a larger cross-sectional area than the nanoposts provided in the regions corresponding to the pixels of other colors . 13. The image sensor of claim 12, wherein the nanoposts provided in the first to fourth regions corresponding to green pixels have a cross-sectional area in the center that is larger than that of the nanoposts provided in the periphery . 16. The image sensor according to claim 1 , wherein the color separation lens array further includes a plurality of first regions and a plurality of second regions that are arranged to protrude from an edge of the sensor substrate and that do not face any of the photosensitive cells of the sensor substrate in the vertical direction. At least one of the first nanoposts and the second nanoposts includes a lower post and an upper post stacked on the lower post;
The image sensor according to claim 1 , wherein the lower post and the upper post are stacked so as to be offset from each other. The image sensor of claim 17 , wherein the degree of misalignment between the lower posts and the upper posts increases from the center to the periphery of the image sensor. an imaging unit that focuses light reflected from a subject to form an optical image;
and the image sensor according to any one of claims 1 to 18 , which converts an optical image formed by the imaging section into an electrical signal. 20. The electronic device of claim 19 , wherein the electronic device is a smartphone, a mobile phone, a personal digital assistant (PDA), a laptop, a personal computer (PC), a home appliance, a security camera, a medical camera, an automobile, or an Internet of Things (IoT) device.